Abstract
The conventional halide gas leak detector uses heated platinum to yield positive ions by direct contact with halide gas. It has therefore some failings: its use in the environment of explosive or combustible gases is strictly forbidden, and its detection sensitivity is not steady, varying largely with surface condition of the platinum,
The purports of this study are
(1) to establish a method of detection free from these failings (Part 1), and
(2) to improve upon the handiness, a remarkable merit, of the conventional detector (Part 2).
In Part 1, the method used is to introduce a mixture of air and halide gas into a proportional counter and to measure the decrease of counting rate of α particles which corresponds to the halide content. The attaching of electrons to halide gas molecules is found to be the main cause of the decrease of counting rate, and from an empirical formula obtained to be consistent with observed results, coefficient of attaching, η, was found for several electro negative gases, SF6, CCl2F2, C2H3Cl and water vapor. In comparison with their known values of 7), the values found in this work (23cm-1 TORR-1 for SF6, 5.3 for CCl2F2, 1.85 for C2H3Cl, and 0.029_??_0.16 for water vapor) are considered to be appropriate which proves that the empirical formula is reasonable.
SF6 was detected with sensitivity of 3×10-5 TORR lit sec-1, the highest among the tested halide gases. This shows that the detecting method adopted is comparable in sensitivity with the conventional method.
